.head{
    height: 100px;
    background-color:red;
    width: 100%;
}
.left{
    float: left;
    width: 30%;
    background-color:blue;
    height: 300px;
}
.right{
    width: 100%;
    height: 300px;
    background-color:aqua;
}
.buttom{
    background-color:gray;
    height:300px;
    width: 100%;
}